In an interview with CNBC, the Yale economics professor says:
"We do have a little bit of bubble thinking… people are very impressed by high tech, probably too impressed…. I like to look at long-term earnings. You can't do that with WhatsApp. That's for adventurers. I'm more of a stable investor who looks at long history and looks to invest long-term."
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But, does that mean tech stocks have dusted off their Smash Mouth and Sugar Ray CDs and are starting to reminisce about the final years of the last millennium? After all, the NASDAQ Composite index's 2013 return of 38% wasn't even the second-best performance since the tech bubble burst in 2000. In 2003, the NASDAQ Composite was up 50%; in 2009, it was up almost 44%. However, those both happened a year after huge losses (31.5% in 2002 and 40.5% in 2008).
Talking Numbers contributor Richard Ross, Global Technical Strategist at Auerbach Grayson, thinks this isn't a replay of yesteryear.
"This is an entirely different market," says Ross. "While we are seeing pockets of euphoria – and we're seeing price tags on some of these acquisitions that might leave some scratching their heads – I see a very healthy advance, what I would call a bull market, not a bubble."
For Ross, the magnitude of the NASDAQ Composite's current bull run doesn't match what it did in the 1990s. From January 1, 1990 to its March 10 high, the index was up over 1,000% when it hit its all-time high of 5,048.62. On the other hand, since the market bottom in March 2009, the NASDAQ composite is up 231%.
"This is not a bubble," says Ross. "This is a buying opportunity. Play the momentum. There's nothing wrong with that. Tech is hot right now and it should continue to do so. You're going to retest that old high at 5,000 as inconceivable as it once seemed to be."
CNBC contributor Andrew Busch, editor and publisher of The Busch Update, thinks the bubble isn't in tech in general that needs to be watched.
"It's really not high tech," says Busch. "It's social media. You get into these buyouts that are kind of crazy, like WhatsApp from Facebook. But, you've got to remember that Facebook is overaggressive and pretty much overfunded with their stock price level so they can engage in these types of activities."
(See: CNBC's Social Media coverage)
Busch notes the Global X Social Media Index ETF (the SOCL), was up over 60%, over 20% higher than the NASDAQ Composite. That distinction leads Busch to say tech as whole isn't effervescent just yet.
"I don't see this as a massive bubble," says Busch. "It's always really difficult to call it. But, we'll start to see some weakness there and you'll get a chance to sell before it really turns into something ugly."
To see the rest of the discussion on the NASDAQ Composite with Ross on the technicals and Busch on the fundamentals, watch the video above.